//
// Copyright (C) 2024 EA group inc.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
//
// Created by jeff on 24-6-4.
//

#pragma once

#include <turbo/container/small_vector.h>
#include <turbo/base/macros.h>
#include <algorithm>
#include <array>
#include <cassert>
#include <cstddef>
#include <initializer_list>
#include <iterator>
#include <memory>
#include <type_traits>
#include <vector>

namespace turbo {
    template<typename T>
    class [[nodiscard]] MutableArrayRef;

    /// ArrayRef - Represent a constant reference to an array (0 or more elements
    /// consecutively in memory), i.e. a start pointer and a length.  It allows
    /// various APIs to take consecutive elements easily and conveniently.
    ///
    /// This class does not own the underlying data, it is expected to be used in
    /// situations where the data resides in some other buffer, whose lifetime
    /// extends past that of the ArrayRef. For this reason, it is not in general
    /// safe to store an ArrayRef.
    ///
    /// This is intended to be trivially copyable, so it should be passed by
    /// value.
    template<typename T>
    class TURBO_GSL_POINTER [[nodiscard]] ArrayRef {
    public:
        using value_type = T;
        using pointer = value_type *;
        using const_pointer = const value_type *;
        using reference = value_type &;
        using const_reference = const value_type &;
        using iterator = const_pointer;
        using const_iterator = const_pointer;
        using reverse_iterator = std::reverse_iterator<iterator>;
        using const_reverse_iterator = std::reverse_iterator<const_iterator>;
        using size_type = size_t;
        using difference_type = ptrdiff_t;

    private:
        /// The start of the array, in an external buffer.
        const T *Data = nullptr;

        /// The number of elements.
        size_type Length = 0;

    public:
        /// @name Constructors
        /// @{

        /// Construct an empty ArrayRef.
        /*implicit*/ ArrayRef() = default;

        /// Construct an empty ArrayRef from std::nullopt.
        /*implicit*/ ArrayRef(std::nullopt_t) {}

        /// Construct an ArrayRef from a single element.
        /*implicit*/ ArrayRef(const T &OneElt)
                : Data(&OneElt), Length(1) {}

        /// Construct an ArrayRef from a pointer and length.
        constexpr /*implicit*/ ArrayRef(const T *data, size_t length)
                : Data(data), Length(length) {}

        /// Construct an ArrayRef from a range.
        constexpr ArrayRef(const T *begin, const T *end)
                : Data(begin), Length(end - begin) {
            assert(begin <= end);
        }

        /// Construct an ArrayRef from a SmallVector. This is templated in order to
        /// avoid instantiating SmallVectorTemplateCommon<T> whenever we
        /// copy-construct an ArrayRef.
        template<typename U>
        /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec)
                : Data(Vec.data()), Length(Vec.size()) {
        }

        /// Construct an ArrayRef from a std::vector.
        template<typename A>
        /*implicit*/ ArrayRef(const std::vector<T, A> &Vec)
                : Data(Vec.data()), Length(Vec.size()) {}

        /// Construct an ArrayRef from a std::array
        template<size_t N>
        /*implicit*/ constexpr ArrayRef(const std::array<T, N> &Arr)
                : Data(Arr.data()), Length(N) {}

        /// Construct an ArrayRef from a C array.
        template<size_t N>
        /*implicit*/ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {}

        /// Construct an ArrayRef from a std::initializer_list.
#if TURBO_GNUC_PREREQ(9, 0, 0)
        // Disable gcc's warning in this constructor as it generates an enormous amount
// of messages. Anyone using ArrayRef should already be aware of the fact that
// it does not do lifetime extension.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Winit-list-lifetime"
#endif

        constexpr /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec)
                : Data(Vec.begin() == Vec.end() ? (T *) nullptr : Vec.begin()),
                  Length(Vec.size()) {}

#if TURBO_GNUC_PREREQ(9, 0, 0)
#pragma GCC diagnostic pop
#endif

        /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to
        /// ensure that only ArrayRefs of pointers can be converted.
        template<typename U>
        ArrayRef(const ArrayRef<U *> &A,
                 std::enable_if_t<std::is_convertible<U *const *, T const *>::value>
                 * = nullptr)
                : Data(A.data()), Length(A.size()) {}

        /// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is
        /// templated in order to avoid instantiating SmallVectorTemplateCommon<T>
        /// whenever we copy-construct an ArrayRef.
        template<typename U, typename DummyT>
        /*implicit*/ ArrayRef(
                const SmallVectorTemplateCommon<U *, DummyT> &Vec,
                std::enable_if_t<std::is_convertible<U *const *, T const *>::value> * =
                nullptr)
                : Data(Vec.data()), Length(Vec.size()) {}

        /// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE
        /// to ensure that only vectors of pointers can be converted.
        template<typename U, typename A>
        ArrayRef(const std::vector<U *, A> &Vec,
                 std::enable_if_t<std::is_convertible<U *const *, T const *>::value>
                 * = nullptr)
                : Data(Vec.data()), Length(Vec.size()) {}

        /// @}
        /// @name Simple Operations
        /// @{

        iterator begin() const { return Data; }

        iterator end() const { return Data + Length; }

        reverse_iterator rbegin() const { return reverse_iterator(end()); }

        reverse_iterator rend() const { return reverse_iterator(begin()); }

        /// empty - Check if the array is empty.
        bool empty() const { return Length == 0; }

        const T *data() const { return Data; }

        /// size - Get the array size.
        size_t size() const { return Length; }

        /// front - Get the first element.
        const T &front() const {
            assert(!empty());
            return Data[0];
        }

        /// back - Get the last element.
        const T &back() const {
            assert(!empty());
            return Data[Length - 1];
        }

        // copy - Allocate copy in Allocator and return ArrayRef<T> to it.
        template<typename Allocator>
        MutableArrayRef<T> copy(Allocator &A) {
            T *Buff = A.template Allocate<T>(Length);
            std::uninitialized_copy(begin(), end(), Buff);
            return MutableArrayRef<T>(Buff, Length);
        }

        /// equals - Check for element-wise equality.
        bool equals(ArrayRef RHS) const {
            if (Length != RHS.Length)
                return false;
            return std::equal(begin(), end(), RHS.begin());
        }

        /// slice(n, m) - Chop off the first N elements of the array, and keep M
        /// elements in the array.
        ArrayRef<T> slice(size_t N, size_t M) const {
            assert(N + M <= size() && "Invalid specifier");
            return ArrayRef<T>(data() + N, M);
        }

        /// slice(n) - Chop off the first N elements of the array.
        ArrayRef<T> slice(size_t N) const { return slice(N, size() - N); }

        /// Drop the first \p N elements of the array.
        ArrayRef<T> drop_front(size_t N = 1) const {
            assert(size() >= N && "Dropping more elements than exist");
            return slice(N, size() - N);
        }

        /// Drop the last \p N elements of the array.
        ArrayRef<T> drop_back(size_t N = 1) const {
            assert(size() >= N && "Dropping more elements than exist");
            return slice(0, size() - N);
        }

        /// Return a copy of *this with the first N elements satisfying the
        /// given predicate removed.
        template<class PredicateT>
        ArrayRef<T> drop_while(PredicateT Pred) const {
            return ArrayRef<T>(find_if_not(*this, Pred), end());
        }

        /// Return a copy of *this with the first N elements not satisfying
        /// the given predicate removed.
        template<class PredicateT>
        ArrayRef<T> drop_until(PredicateT Pred) const {
            return ArrayRef<T>(find_if(*this, Pred), end());
        }

        /// Return a copy of *this with only the first \p N elements.
        ArrayRef<T> take_front(size_t N = 1) const {
            if (N >= size())
                return *this;
            return drop_back(size() - N);
        }

        /// Return a copy of *this with only the last \p N elements.
        ArrayRef<T> take_back(size_t N = 1) const {
            if (N >= size())
                return *this;
            return drop_front(size() - N);
        }

        /// Return the first N elements of this Array that satisfy the given
        /// predicate.
        template<class PredicateT>
        ArrayRef<T> take_while(PredicateT Pred) const {
            return ArrayRef<T>(begin(), find_if_not(*this, Pred));
        }

        /// Return the first N elements of this Array that don't satisfy the
        /// given predicate.
        template<class PredicateT>
        ArrayRef<T> take_until(PredicateT Pred) const {
            return ArrayRef<T>(begin(), find_if(*this, Pred));
        }

        /// @}
        /// @name Operator Overloads
        /// @{
        const T &operator[](size_t Index) const {
            assert(Index < Length && "Invalid index!");
            return Data[Index];
        }

        /// Disallow accidental assignment from a temporary.
        ///
        /// The declaration here is extra complicated so that "arrayRef = {}"
        /// continues to select the move assignment operator.
        template<typename U>
        std::enable_if_t<std::is_same<U, T>::value, ArrayRef<T>> &
        operator=(U &&Temporary) = delete;

        /// Disallow accidental assignment from a temporary.
        ///
        /// The declaration here is extra complicated so that "arrayRef = {}"
        /// continues to select the move assignment operator.
        template<typename U>
        std::enable_if_t<std::is_same<U, T>::value, ArrayRef<T>> &
        operator=(std::initializer_list<U>) = delete;

        /// @}
        /// @name Expensive Operations
        /// @{
        std::vector<T> vec() const {
            return std::vector<T>(Data, Data + Length);
        }

        /// @}
        /// @name Conversion operators
        /// @{
        operator std::vector<T>() const {
            return std::vector<T>(Data, Data + Length);
        }

        /// @}
    };

    /// MutableArrayRef - Represent a mutable reference to an array (0 or more
    /// elements consecutively in memory), i.e. a start pointer and a length.  It
    /// allows various APIs to take and modify consecutive elements easily and
    /// conveniently.
    ///
    /// This class does not own the underlying data, it is expected to be used in
    /// situations where the data resides in some other buffer, whose lifetime
    /// extends past that of the MutableArrayRef. For this reason, it is not in
    /// general safe to store a MutableArrayRef.
    ///
    /// This is intended to be trivially copyable, so it should be passed by
    /// value.
    template<typename T>
    class [[nodiscard]] MutableArrayRef : public ArrayRef<T> {
    public:
        using value_type = T;
        using pointer = value_type *;
        using const_pointer = const value_type *;
        using reference = value_type &;
        using const_reference = const value_type &;
        using iterator = pointer;
        using const_iterator = const_pointer;
        using reverse_iterator = std::reverse_iterator<iterator>;
        using const_reverse_iterator = std::reverse_iterator<const_iterator>;
        using size_type = size_t;
        using difference_type = ptrdiff_t;

        /// Construct an empty MutableArrayRef.
        /*implicit*/ MutableArrayRef() = default;

        /// Construct an empty MutableArrayRef from std::nullopt.
        /*implicit*/ MutableArrayRef(std::nullopt_t) : ArrayRef<T>() {}

        /// Construct a MutableArrayRef from a single element.
        /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {}

        /// Construct a MutableArrayRef from a pointer and length.
        /*implicit*/ MutableArrayRef(T *data, size_t length)
                : ArrayRef<T>(data, length) {}

        /// Construct a MutableArrayRef from a range.
        MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {}

        /// Construct a MutableArrayRef from a SmallVector.
        /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec)
                : ArrayRef<T>(Vec) {}

        /// Construct a MutableArrayRef from a std::vector.
        /*implicit*/ MutableArrayRef(std::vector<T> &Vec)
                : ArrayRef<T>(Vec) {}

        /// Construct a MutableArrayRef from a std::array
        template<size_t N>
        /*implicit*/ constexpr MutableArrayRef(std::array<T, N> &Arr)
                : ArrayRef<T>(Arr) {}

        /// Construct a MutableArrayRef from a C array.
        template<size_t N>
        /*implicit*/ constexpr MutableArrayRef(T (&Arr)[N]) : ArrayRef<T>(Arr) {}

        T *data() const { return const_cast<T *>(ArrayRef<T>::data()); }

        iterator begin() const { return data(); }

        iterator end() const { return data() + this->size(); }

        reverse_iterator rbegin() const { return reverse_iterator(end()); }

        reverse_iterator rend() const { return reverse_iterator(begin()); }

        /// front - Get the first element.
        T &front() const {
            assert(!this->empty());
            return data()[0];
        }

        /// back - Get the last element.
        T &back() const {
            assert(!this->empty());
            return data()[this->size() - 1];
        }

        /// slice(n, m) - Chop off the first N elements of the array, and keep M
        /// elements in the array.
        MutableArrayRef<T> slice(size_t N, size_t M) const {
            assert(N + M <= this->size() && "Invalid specifier");
            return MutableArrayRef<T>(this->data() + N, M);
        }

        /// slice(n) - Chop off the first N elements of the array.
        MutableArrayRef<T> slice(size_t N) const {
            return slice(N, this->size() - N);
        }

        /// Drop the first \p N elements of the array.
        MutableArrayRef<T> drop_front(size_t N = 1) const {
            assert(this->size() >= N && "Dropping more elements than exist");
            return slice(N, this->size() - N);
        }

        MutableArrayRef<T> drop_back(size_t N = 1) const {
            assert(this->size() >= N && "Dropping more elements than exist");
            return slice(0, this->size() - N);
        }

        /// Return a copy of *this with the first N elements satisfying the
        /// given predicate removed.
        template<class PredicateT>
        MutableArrayRef<T> drop_while(PredicateT Pred) const {
            return MutableArrayRef<T>(find_if_not(*this, Pred), end());
        }

        /// Return a copy of *this with the first N elements not satisfying
        /// the given predicate removed.
        template<class PredicateT>
        MutableArrayRef<T> drop_until(PredicateT Pred) const {
            return MutableArrayRef<T>(find_if(*this, Pred), end());
        }

        /// Return a copy of *this with only the first \p N elements.
        MutableArrayRef<T> take_front(size_t N = 1) const {
            if (N >= this->size())
                return *this;
            return drop_back(this->size() - N);
        }

        /// Return a copy of *this with only the last \p N elements.
        MutableArrayRef<T> take_back(size_t N = 1) const {
            if (N >= this->size())
                return *this;
            return drop_front(this->size() - N);
        }

        /// Return the first N elements of this Array that satisfy the given
        /// predicate.
        template<class PredicateT>
        MutableArrayRef<T> take_while(PredicateT Pred) const {
            return MutableArrayRef<T>(begin(), find_if_not(*this, Pred));
        }

        /// Return the first N elements of this Array that don't satisfy the
        /// given predicate.
        template<class PredicateT>
        MutableArrayRef<T> take_until(PredicateT Pred) const {
            return MutableArrayRef<T>(begin(), find_if(*this, Pred));
        }

        /// @}
        /// @name Operator Overloads
        /// @{
        T &operator[](size_t Index) const {
            assert(Index < this->size() && "Invalid index!");
            return data()[Index];
        }
    };

    /// This is a MutableArrayRef that owns its array.
    template<typename T>
    class OwningArrayRef : public MutableArrayRef<T> {
    public:
        OwningArrayRef() = default;

        OwningArrayRef(size_t Size) : MutableArrayRef<T>(new T[Size], Size) {}

        OwningArrayRef(ArrayRef<T> Data)
                : MutableArrayRef<T>(new T[Data.size()], Data.size()) {
            std::copy(Data.begin(), Data.end(), this->begin());
        }

        OwningArrayRef(OwningArrayRef &&Other) { *this = std::move(Other); }

        OwningArrayRef &operator=(OwningArrayRef &&Other) {
            delete[] this->data();
            this->MutableArrayRef<T>::operator=(Other);
            Other.MutableArrayRef<T>::operator=(MutableArrayRef<T>());
            return *this;
        }

        ~OwningArrayRef() { delete[] this->data(); }
    };

    /// @name ArrayRef Deduction guides
    /// @{
    /// Deduction guide to construct an ArrayRef from a single element.
    template<typename T> ArrayRef(const T &OneElt) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a pointer and length
    template<typename T> ArrayRef(const T *data, size_t length) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a range
    template<typename T> ArrayRef(const T *data, const T *end) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a SmallVector
    template<typename T> ArrayRef(const SmallVectorImpl<T> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a SmallVector
    template<typename T, unsigned N>
    ArrayRef(const SmallVector<T, N> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a std::vector
    template<typename T> ArrayRef(const std::vector<T> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a std::array
    template<typename T, std::size_t N>
    ArrayRef(const std::array<T, N> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from an ArrayRef (const)
    template<typename T> ArrayRef(const ArrayRef<T> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from an ArrayRef
    template<typename T> ArrayRef(ArrayRef<T> &Vec) -> ArrayRef<T>;

    /// Deduction guide to construct an ArrayRef from a C array.
    template<typename T, size_t N> ArrayRef(const T (&Arr)[N]) -> ArrayRef<T>;

    /// @}

    /// @name ArrayRef Convenience constructors
    /// @{
    /// Construct an ArrayRef from a single element.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const T &OneElt) {
        return OneElt;
    }

    /// Construct an ArrayRef from a pointer and length.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const T *data, size_t length) {
        return ArrayRef<T>(data, length);
    }

    /// Construct an ArrayRef from a range.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const T *begin, const T *end) {
        return ArrayRef<T>(begin, end);
    }

    /// Construct an ArrayRef from a SmallVector.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) {
        return Vec;
    }

    /// Construct an ArrayRef from a SmallVector.
    template<typename T, unsigned N>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) {
        return Vec;
    }

    /// Construct an ArrayRef from a std::vector.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) {
        return Vec;
    }

    /// Construct an ArrayRef from a std::array.
    template<typename T, std::size_t N>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const std::array<T, N> &Arr) {
        return Arr;
    }

    /// Construct an ArrayRef from an ArrayRef (no-op) (const)
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) {
        return Vec;
    }

    /// Construct an ArrayRef from an ArrayRef (no-op)
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> &makeArrayRef(ArrayRef<T> &Vec) {
        return Vec;
    }

    /// Construct an ArrayRef from a C array.
    template<typename T, size_t N>
    TURBO_DEPRECATED("Use deduction guide instead ArrayRef")
    ArrayRef<T> makeArrayRef(const T (&Arr)[N]) {
        return ArrayRef<T>(Arr);
    }

    /// @name MutableArrayRef Deduction guides
    /// @{
    /// Deduction guide to construct a `MutableArrayRef` from a single element
    template<class T> MutableArrayRef(T &OneElt) -> MutableArrayRef<T>;

    /// Deduction guide to construct a `MutableArrayRef` from a pointer and
    /// length.
    template<class T>
    MutableArrayRef(T *data, size_t length) -> MutableArrayRef<T>;

    /// Deduction guide to construct a `MutableArrayRef` from a `SmallVector`.
    template<class T>
    MutableArrayRef(SmallVectorImpl<T> &Vec) -> MutableArrayRef<T>;

    template<class T, unsigned N>
    MutableArrayRef(SmallVector<T, N> &Vec) -> MutableArrayRef<T>;

    /// Deduction guide to construct a `MutableArrayRef` from a `std::vector`.
    template<class T> MutableArrayRef(std::vector<T> &Vec) -> MutableArrayRef<T>;

    /// Deduction guide to construct a `MutableArrayRef` from a `std::array`.
    template<class T, std::size_t N>
    MutableArrayRef(std::array<T, N> &Vec) -> MutableArrayRef<T>;

    /// Deduction guide to construct a `MutableArrayRef` from a C array.
    template<typename T, size_t N>
    MutableArrayRef(T (&Arr)[N]) -> MutableArrayRef<T>;

    /// @}

    /// Construct a MutableArrayRef from a single element.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(T &OneElt) {
        return OneElt;
    }

    /// Construct a MutableArrayRef from a pointer and length.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(T *data, size_t length) {
        return MutableArrayRef<T>(data, length);
    }

    /// Construct a MutableArrayRef from a SmallVector.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(SmallVectorImpl<T> &Vec) {
        return Vec;
    }

    /// Construct a MutableArrayRef from a SmallVector.
    template<typename T, unsigned N>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(SmallVector<T, N> &Vec) {
        return Vec;
    }

    /// Construct a MutableArrayRef from a std::vector.
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(std::vector<T> &Vec) {
        return Vec;
    }

    /// Construct a MutableArrayRef from a std::array.
    template<typename T, std::size_t N>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(std::array<T, N> &Arr) {
        return Arr;
    }

    /// Construct a MutableArrayRef from a MutableArrayRef (no-op) (const)
    template<typename T>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(const MutableArrayRef<T> &Vec) {
        return Vec;
    }

    /// Construct a MutableArrayRef from a C array.
    template<typename T, size_t N>
    TURBO_DEPRECATED("Use deduction guide instead MutableArrayRef")
    MutableArrayRef<T> makeMutableArrayRef(T (&Arr)[N]) {
        return MutableArrayRef<T>(Arr);
    }

    /// @}
    /// @name ArrayRef Comparison Operators
    /// @{

    template<typename T>
    inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) {
        return LHS.equals(RHS);
    }

    template<typename T>
    inline bool operator==(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
        return ArrayRef<T>(LHS).equals(RHS);
    }

    template<typename T>
    inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) {
        return !(LHS == RHS);
    }

    template<typename T>
    inline bool operator!=(SmallVectorImpl<T> &LHS, ArrayRef<T> RHS) {
        return !(LHS == RHS);
    }

} // end namespace turbo
